Listen before talk based resource modification and reduced channel occupancy time sharing signaling for sidelink communication in unlicensed spectrum

ABSTRACT

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may select, within a resource selection window, a set of resources in which to transmit over an unlicensed sidelink channel. The UE may attempt a listen before talk (LBT) procedure to initiate a channel occupancy time in which to transmit over the unlicensed sidelink channel. The UE may adjust, within at least a portion of the resource selection window, the set of resources in which to transmit over the unlicensed sidelink channel to be contiguous in at least a time domain based at least in part on the LBT procedure succeeding. The UE may transmit, over the unlicensed sidelink channel, using the set of resources that are adjusted to be contiguous in at least the time domain. Numerous other aspects are provided.

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wirelesscommunication and to techniques and apparatuses for listen before talk(LBT) based resource modification and reduced channel occupancy time(COT) sharing signaling for sidelink communication in unlicensedspectrum.

BACKGROUND

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power, or the like). Examples of such multiple-accesstechnologies include code division multiple access (CDMA) systems, timedivision multiple access (TDMA) systems, frequency-division multipleaccess (FDMA) systems, orthogonal frequency-division multiple access(OFDMA) systems, single-carrier frequency-division multiple access(SC-FDMA) systems, time division synchronous code division multipleaccess (TD-SCDMA) systems, and Long Term Evolution (LTE).LTE/LTE-Advanced is a set of enhancements to the Universal MobileTelecommunications System (UMTS) mobile standard promulgated by theThird Generation Partnership Project (3GPP).

A wireless network may include a number of base stations (BSs) that cansupport communication for a number of user equipment (UEs). A userequipment (UE) may communicate with a base station (BS) via the downlinkand uplink. The downlink (or forward link) refers to the communicationlink from the BS to the UE, and the uplink (or reverse link) refers tothe communication link from the UE to the BS. As will be described inmore detail herein, a BS may be referred to as a Node B, a gNB, anaccess point (AP), a radio head, a transmit receive point (TRP), a NewRadio (NR) BS, a 5G Node B, or the like.

The above multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent user equipment to communicate on a municipal, national,regional, and even global level. New Radio (NR), which may also bereferred to as 5G, is a set of enhancements to the LTE mobile standardpromulgated by the Third Generation Partnership Project (3GPP). NR isdesigned to better support mobile broadband Internet access by improvingspectral efficiency, lowering costs, improving services, making use ofnew spectrum, and better integrating with other open standards usingorthogonal frequency division multiplexing (OFDM) with a cyclic prefix(CP) (CP-OFDM) on the downlink (DL), using CP-OFDM and/or SC-FDM (e.g.,also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) onthe uplink (UL), as well as supporting beamforming, multiple-inputmultiple-output (MIMO) antenna technology, and carrier aggregation. Asthe demand for mobile broadband access continues to increase, furtherimprovements in LTE, NR, and other radio access technologies remainuseful.

SUMMARY

In some aspects, a method of wireless communication performed by a userequipment (UE) includes selecting, within a resource selection window, aset of resources in which to transmit over an unlicensed sidelinkchannel; attempting a listen before talk (LBT) procedure to initiate achannel occupancy time (COT) in which to transmit over the unlicensedsidelink channel; adjusting, within at least a portion of the resourceselection window, the set of resources in which to transmit over theunlicensed sidelink channel to be contiguous in at least a time domainbased at least in part on the LBT procedure succeeding; andtransmitting, over the unlicensed sidelink channel, using the set ofresources that are adjusted to be contiguous in at least the timedomain.

In some aspects, a UE for wireless communication includes a memory andone or more processors operatively coupled to the memory, the memory andthe one or more processors configured to: select, within a resourceselection window, a set of resources in which to transmit over anunlicensed sidelink channel; attempt an LBT procedure to initiate a COTin which to transmit over the unlicensed sidelink channel; adjust,within at least a portion of the resource selection window, the set ofresources in which to transmit over the unlicensed sidelink channel tobe contiguous in at least a time domain based at least in part on theLBT procedure succeeding; and transmit, over the unlicensed sidelinkchannel, using the set of resources that are adjusted to be contiguousin at least the time domain.

In some aspects, a non-transitory computer-readable medium storing a setof instructions for wireless communication includes one or moreinstructions that, when executed by one or more processors of a UE,cause the UE to: select, within a resource selection window, a set ofresources in which to transmit over an unlicensed sidelink channel;attempt an LBT procedure to initiate a COT in which to transmit over theunlicensed sidelink channel; adjust, within at least a portion of theresource selection window, the set of resources in which to transmitover the unlicensed sidelink channel to be contiguous in at least a timedomain based at least in part on the LBT procedure succeeding; andtransmit, over the unlicensed sidelink channel, using the set ofresources that are adjusted to be contiguous in at least the timedomain.

In some aspects, an apparatus for wireless communication includes meansfor selecting, within a resource selection window, a set of resources inwhich to transmit over an unlicensed sidelink channel; means forattempting an LBT procedure to initiate a COT in which to transmit overthe unlicensed sidelink channel; means for adjusting, within at least aportion of the resource selection window, the set of resources in whichto transmit over the unlicensed sidelink channel to be contiguous in atleast a time domain based at least in part on the LBT proceduresucceeding; and means for transmitting, over the unlicensed sidelinkchannel, using the set of resources that are adjusted to be contiguousin at least the time domain.

Aspects generally include a method, apparatus, system, computer programproduct, non-transitory computer-readable medium, user equipment, basestation, wireless communication device, and/or processing system assubstantially described herein with reference to and as illustrated bythe drawings and specification.

The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described hereinafter. The conceptionand specific examples disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present disclosure. Such equivalent constructions do notdepart from the scope of the appended claims. Characteristics of theconcepts disclosed herein, both their organization and method ofoperation, together with associated advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. Each of the figures is provided for the purposesof illustration and description, and not as a definition of the limitsof the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above-recited features of the present disclosure can beunderstood in detail, a more particular description, briefly summarizedabove, may be had by reference to aspects, some of which are illustratedin the appended drawings. It is to be noted, however, that the appendeddrawings illustrate only certain typical aspects of this disclosure andare therefore not to be considered limiting of its scope, for thedescription may admit to other equally effective aspects. The samereference numbers in different drawings may identify the same or similarelements.

FIG. 1 is a diagram illustrating an example of a wireless network, inaccordance with various aspects of the present disclosure.

FIG. 2 is a diagram illustrating an example of a base station incommunication with a UE in a wireless network, in accordance withvarious aspects of the present disclosure.

FIG. 3 is a diagram illustrating an example of sidelink communication,in accordance with various aspects of the present disclosure.

FIGS. 4A-4B are diagrams illustrating examples of channel occupancy time(COT) sharing for sidelink communication in unlicensed spectrum, inaccordance with various aspects of the present disclosure.

FIG. 5 is a diagram illustrating an example associated with listenbefore talk (LBT) based resource modification for sidelink communicationin unlicensed spectrum, in accordance with various aspects of thepresent disclosure.

FIGS. 6A-6B are diagrams illustrating examples associated with reducedCOT sharing signaling for sidelink communication in unlicensed spectrum,in accordance with various aspects of the present disclosure.

FIG. 7 is a diagram illustrating an example process associated withLBT-based resource modification and reduced COT sharing signaling forsidelink communication in unlicensed spectrum, in accordance withvarious aspects of the present disclosure.

FIG. 8 is a block diagram of an example apparatus for wirelesscommunication, in accordance with various aspects of the presentdisclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and should not be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein, one skilled in the art should appreciate that thescope of the disclosure is intended to cover any aspect of thedisclosure disclosed herein, whether implemented independently of orcombined with any other aspect of the disclosure. For example, anapparatus may be implemented or a method may be practiced using anynumber of the aspects set forth herein. In addition, the scope of thedisclosure is intended to cover such an apparatus or method which ispracticed using other structure, functionality, or structure andfunctionality in addition to or other than the various aspects of thedisclosure set forth herein. It should be understood that any aspect ofthe disclosure disclosed herein may be embodied by one or more elementsof a claim.

Several aspects of telecommunication systems will now be presented withreference to various apparatuses and techniques. These apparatuses andtechniques will be described in the following detailed description andillustrated in the accompanying drawings by various blocks, modules,components, circuits, steps, processes, algorithms, or the like(collectively referred to as “elements”). These elements may beimplemented using hardware, software, or combinations thereof. Whethersuch elements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

It should be noted that while aspects may be described herein usingterminology commonly associated with a 5G or NR radio access technology(RAT), aspects of the present disclosure can be applied to other RATs,such as a 3G RAT, a 4G RAT, and/or a RAT subsequent to 5G (e.g., 6G).

FIG. 1 is a diagram illustrating an example of a wireless network 100,in accordance with various aspects of the present disclosure. Thewireless network 100 may be or may include elements of a 5G (NR) networkand/or an LTE network, among other examples. The wireless network 100may include a number of base stations 110 (shown as BS 110 a, BS 110 b,BS 110 c, and BS 110 d) and other network entities. A base station (BS)is an entity that communicates with user equipment (UEs) and may also bereferred to as an NR BS, a Node B, a gNB, a 5G node B (NB), an accesspoint, a transmit receive point (TRP), or the like. Each BS may providecommunication coverage for a particular geographic area. In 3GPP, theterm “cell” can refer to a coverage area of a BS and/or a BS subsystemserving this coverage area, depending on the context in which the termis used.

A BS may provide communication coverage for a macro cell, a pico cell, afemto cell, and/or another type of cell. A macro cell may cover arelatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs with service subscription. Apico cell may cover a relatively small geographic area and may allowunrestricted access by UEs with service subscription. A femto cell maycover a relatively small geographic area (e.g., a home) and may allowrestricted access by UEs having association with the femto cell (e.g.,UEs in a closed subscriber group (CSG)). ABS for a macro cell may bereferred to as a macro BS. ABS for a pico cell may be referred to as apico BS. A BS for a femto cell may be referred to as a femto BS or ahome BS. In the example shown in FIG. 1, a BS 110 a may be a macro BSfor a macro cell 102 a, a BS 110 b may be a pico BS for a pico cell 102b, and a BS 110 c may be a femto BS for a femto cell 102 c. A BS maysupport one or multiple (e.g., three) cells. The terms “eNB”, “basestation”, “NR BS”, “gNB”, “TRP”, “AP”, “node B”, “5G NB”, and “cell” maybe used interchangeably herein.

In some aspects, a cell may not necessarily be stationary, and thegeographic area of the cell may move according to the location of amobile BS. In some aspects, the BSs may be interconnected to one anotherand/or to one or more other BSs or network nodes (not shown) in thewireless network 100 through various types of backhaul interfaces, suchas a direct physical connection or a virtual network, using any suitabletransport network.

Wireless network 100 may also include relay stations. A relay station isan entity that can receive a transmission of data from an upstreamstation (e.g., a BS or a UE) and send a transmission of the data to adownstream station (e.g., a UE or a BS). A relay station may also be aUE that can relay transmissions for other UEs. In the example shown inFIG. 1, a relay BS 110 d may communicate with macro BS 110 a and a UE120 d in order to facilitate communication between BS 110 a and UE 120d. A relay BS may also be referred to as a relay station, a relay basestation, a relay, or the like.

Wireless network 100 may be a heterogeneous network that includes BSs ofdifferent types, such as macro BSs, pico BSs, femto BSs, relay BSs, orthe like. These different types of BSs may have different transmit powerlevels, different coverage areas, and different impacts on interferencein wireless network 100. For example, macro BSs may have a high transmitpower level (e.g., 5 to 40 watts) whereas pico BSs, femto BSs, and relayBSs may have lower transmit power levels (e.g., 0.1 to 2 watts).

A network controller 130 may couple to a set of BSs and may providecoordination and control for these BSs. Network controller 130 maycommunicate with the BSs via a backhaul. The BSs may also communicatewith one another, directly or indirectly, via a wireless or wirelinebackhaul.

UEs 120 (e.g., 120 a, 120 b, 120 c) may be dispersed throughout wirelessnetwork 100, and each UE may be stationary or mobile. A UE may also bereferred to as an access terminal, a terminal, a mobile station, asubscriber unit, a station, or the like. A UE may be a cellular phone(e.g., a smart phone), a personal digital assistant (PDA), a wirelessmodem, a wireless communication device, a handheld device, a laptopcomputer, a cordless phone, a wireless local loop (WLL) station, atablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook,a medical device or equipment, biometric sensors/devices, wearabledevices (smart watches, smart clothing, smart glasses, smart wristbands, smart jewelry (e.g., smart ring, smart bracelet)), anentertainment device (e.g., a music or video device, or a satelliteradio), a vehicular component or sensor, smart meters/sensors,industrial manufacturing equipment, a global positioning system device,or any other suitable device that is configured to communicate via awireless or wired medium.

Some UEs may be considered machine-type communication (MTC) or evolvedor enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEsinclude, for example, robots, drones, remote devices, sensors, meters,monitors, and/or location tags, that may communicate with a basestation, another device (e.g., remote device), or some other entity. Awireless node may provide, for example, connectivity for or to a network(e.g., a wide area network such as Internet or a cellular network) via awired or wireless communication link. Some UEs may be consideredInternet-of-Things (IoT) devices, and/or may be implemented as NB-IoT(narrowband internet of things) devices. Some UEs may be considered aCustomer Premises Equipment (CPE). UE 120 may be included inside ahousing that houses components of UE 120, such as processor componentsand/or memory components. In some aspects, the processor components andthe memory components may be coupled together. For example, theprocessor components (e.g., one or more processors) and the memorycomponents (e.g., a memory) may be operatively coupled, communicativelycoupled, electronically coupled, and/or electrically coupled.

In general, any number of wireless networks may be deployed in a givengeographic area. Each wireless network may support a particular RAT andmay operate on one or more frequencies. A RAT may also be referred to asa radio technology, an air interface, or the like. A frequency may alsobe referred to as a carrier, a frequency channel, or the like. Eachfrequency may support a single RAT in a given geographic area in orderto avoid interference between wireless networks of different RATs. Insome cases, NR or 5G RAT networks may be deployed.

In some aspects, two or more UEs 120 (e.g., shown as UE 120 a and UE 120e) may communicate directly using one or more sidelink channels (e.g.,without using a base station 110 as an intermediary to communicate withone another). For example, the UEs 120 may communicate usingpeer-to-peer (P2P) communications, device-to-device (D2D)communications, a vehicle-to-everything (V2X) protocol (e.g., which mayinclude a vehicle-to-vehicle (V2V) protocol or avehicle-to-infrastructure (V2I) protocol), and/or a mesh network. Inthis case, the UE 120 may perform scheduling operations, resourceselection operations, and/or other operations described elsewhere hereinas being performed by the base station 110.

Devices of wireless network 100 may communicate using theelectromagnetic spectrum, which may be subdivided based on frequency orwavelength into various classes, bands, channels, or the like. Forexample, devices of wireless network 100 may communicate using anoperating band having a first frequency range (FR1), which may span from410 MHz to 7.125 GHz, and/or may communicate using an operating bandhaving a second frequency range (FR2), which may span from 24.25 GHz to52.6 GHz. The frequencies between FR1 and FR2 are sometimes referred toas mid-band frequencies. Although a portion of FR1 is greater than 6GHz, FR1 is often referred to as a “sub-6 GHz” band. Similarly, FR2 isoften referred to as a “millimeter wave” band despite being differentfrom the extremely high frequency (EHF) band (30 GHz-300 GHz) which isidentified by the International Telecommunications Union (ITU) as a“millimeter wave” band. Thus, unless specifically stated otherwise, itshould be understood that the term “sub-6 GHz” or the like, if usedherein, may broadly represent frequencies less than 6 GHz, frequencieswithin FR1, and/or mid-band frequencies (e.g., greater than 7.125 GHz).Similarly, unless specifically stated otherwise, it should be understoodthat the term “millimeter wave” or the like, if used herein, may broadlyrepresent frequencies within the EHF band, frequencies within FR2,and/or mid-band frequencies (e.g., less than 24.25 GHz). It iscontemplated that the frequencies included in FR1 and FR2 may bemodified, and techniques described herein are applicable to thosemodified frequency ranges.

In some aspects, the operating band that devices of wireless network 100use to communicate may include an operating band in a licensed radiofrequency spectrum and/or an operating band in an unlicensed radiofrequency spectrum. For example, a base station 110 and a UE 120 maycommunicate in an unlicensed radio frequency spectrum using a RAT suchas Licensed-Assisted Access (LAA), Enhanced LAA (eLAA), Further EnhancedLAA (feLAA), MulteFire, and/or NR-Unlicensed (NR-U), among otherexamples. In some aspects, an operating band in an unlicensed radiofrequency spectrum may be shared by one or more base stations 110, oneor more UEs 120, and/or one or more wireless local area network (WLAN)devices (not shown). Because the operating band in the unlicensed radiofrequency spectrum may be shared by devices operating under differentprotocols (e.g., different RATs), transmitting devices may need tocontend for access to the operating band in the unlicensed radiofrequency spectrum prior to transmitting over the unlicensed radiofrequency spectrum.

For example, in a shared or unlicensed frequency band, a transmittingdevice may contend against other devices for channel access beforetransmitting on a shared or unlicensed channel to reduce and/or preventcollisions on the shared or unlicensed channel. To contend for channelaccess, the transmitting device may perform a channel access procedure,such as a listen before talk (or listen before transmit) (LBT) procedureor another suitable channel access procedure, for shared or unlicensedfrequency band channel access. The channel access procedure may beperformed to determine whether the physical channel (e.g., the radioresources of the channel) are free to use or are busy (e.g., in use byanother wireless communication device such as another UE, an IoT device,and/or a WLAN device, among other examples). The channel accessprocedure may include sensing or measuring the physical channel (e.g.,performing a reference signal received power (RSRP) measurement,detecting an energy level, or performing another type of measurement)during a channel access gap (which may also be referred to as acontention window) and determining whether the shared or unlicensedchannel is free or busy based at least in part on the signals sensed ormeasured on the physical channel (e.g., based at least in part onwhether the measurement satisfies a threshold). If the transmittingdevice determines that the channel access procedure was successful, thetransmitting device may perform one or more transmissions on the sharedor unlicensed channel during a transmission opportunity (TXOP), whichmay extend for a channel occupancy time (COT).

As indicated above, FIG. 1 is provided as an example. Other examples maydiffer from what is described with regard to FIG. 1.

FIG. 2 is a diagram illustrating an example 200 of a base station 110 incommunication with a UE 120 in a wireless network 100, in accordancewith various aspects of the present disclosure. Base station 110 may beequipped with T antennas 234 a through 234 t, and UE 120 may be equippedwith R antennas 252 a through 252 r, where in general T≥1 and R≥1.

At base station 110, a transmit processor 220 may receive data from adata source 212 for one or more UEs, select one or more modulation andcoding schemes (MCS) for each UE based at least in part on channelquality indicators (CQIs) received from the UE, process (e.g., encodeand modulate) the data for each UE based at least in part on the MCS(s)selected for the UE, and provide data symbols for all UEs. Transmitprocessor 220 may also process system information (e.g., for semi-staticresource partitioning information (SRPI)) and control information (e.g.,CQI requests, grants, and/or upper layer signaling) and provide overheadsymbols and control symbols. Transmit processor 220 may also generatereference symbols for reference signals (e.g., a cell-specific referencesignal (CRS) or a demodulation reference signal (DMRS)) andsynchronization signals (e.g., a primary synchronization signal (PSS) ora secondary synchronization signal (SSS)). A transmit (TX)multiple-input multiple-output (MIMO) processor 230 may perform spatialprocessing (e.g., precoding) on the data symbols, the control symbols,the overhead symbols, and/or the reference symbols, if applicable, andmay provide T output symbol streams to T modulators (MODs) 232 a through232 t. Each modulator 232 may process a respective output symbol stream(e.g., for OFDM) to obtain an output sample stream. Each modulator 232may further process (e.g., convert to analog, amplify, filter, andupconvert) the output sample stream to obtain a downlink signal. Tdownlink signals from modulators 232 a through 232 t may be transmittedvia T antennas 234 a through 234 t, respectively.

At UE 120, antennas 252 a through 252 r may receive the downlink signalsfrom base station 110 and/or other base stations and may providereceived signals to demodulators (DEMODs) 254 a through 254 r,respectively. Each demodulator 254 may condition (e.g., filter, amplify,downconvert, and digitize) a received signal to obtain input samples.Each demodulator 254 may further process the input samples (e.g., forOFDM) to obtain received symbols. A MIMO detector 256 may obtainreceived symbols from all R demodulators 254 a through 254 r, performMIMO detection on the received symbols if applicable, and providedetected symbols. A receive processor 258 may process (e.g., demodulateand decode) the detected symbols, provide decoded data for UE 120 to adata sink 260, and provide decoded control information and systeminformation to a controller/processor 280. The term“controller/processor” may refer to one or more controllers, one or moreprocessors, or a combination thereof. A channel processor may determinea reference signal received power (RSRP) parameter, a received signalstrength indicator (RSSI) parameter, a reference signal received quality(RSRQ) parameter, and/or a channel quality indicator (CQI) parameter,among other examples. In some aspects, one or more components of UE 120may be included in a housing 284.

Network controller 130 may include communication unit 294,controller/processor 290, and memory 292. Network controller 130 mayinclude, for example, one or more devices in a core network. Networkcontroller 130 may communicate with base station 110 via communicationunit 294.

Antennas (e.g., antennas 234 a through 234 t and/or antennas 252 athrough 252 r) may include, or may be included within, one or moreantenna panels, antenna groups, sets of antenna elements, and/or antennaarrays, among other examples. An antenna panel, an antenna group, a setof antenna elements, and/or an antenna array may include one or moreantenna elements. An antenna panel, an antenna group, a set of antennaelements, and/or an antenna array may include a set of coplanar antennaelements and/or a set of non-coplanar antenna elements. An antennapanel, an antenna group, a set of antenna elements, and/or an antennaarray may include antenna elements within a single housing and/orantenna elements within multiple housings. An antenna panel, an antennagroup, a set of antenna elements, and/or an antenna array may includeone or more antenna elements coupled to one or more transmission and/orreception components, such as one or more components of FIG. 2.

On the uplink, at UE 120, a transmit processor 264 may receive andprocess data from a data source 262 and control information (e.g., forreports that include RSRP, RSSI, RSRQ, and/or CQI) fromcontroller/processor 280. Transmit processor 264 may also generatereference symbols for one or more reference signals. The symbols fromtransmit processor 264 may be precoded by a TX MIMO processor 266 ifapplicable, further processed by modulators 254 a through 254 r (e.g.,for DFT-s-OFDM or CP-OFDM), and transmitted to base station 110. In someaspects, a modulator and a demodulator (e.g., MOD/DEMOD 254) of the UE120 may be included in a modem of the UE 120. In some aspects, the UE120 includes a transceiver. The transceiver may include any combinationof antenna(s) 252, modulators and/or demodulators 254, MIMO detector256, receive processor 258, transmit processor 264, and/or TX MIMOprocessor 266. The transceiver may be used by a processor (e.g.,controller/processor 280) and memory 282 to perform aspects of any ofthe methods described herein, for example, as described with referenceto FIG. 5, FIGS. 6A-6B, and/or FIG. 7.

At base station 110, the uplink signals from UE 120 and other UEs may bereceived by antennas 234, processed by demodulators 232, detected by aMIMO detector 236 if applicable, and further processed by a receiveprocessor 238 to obtain decoded data and control information sent by UE120. Receive processor 238 may provide the decoded data to a data sink239 and the decoded control information to controller/processor 240.Base station 110 may include communication unit 244 and communicate tonetwork controller 130 via communication unit 244. Base station 110 mayinclude a scheduler 246 to schedule UEs 120 for downlink and/or uplinkcommunications. In some aspects, a modulator and a demodulator (e.g.,MOD/DEMOD 232) of the base station 110 may be included in a modem of thebase station 110. In some aspects, the base station 110 includes atransceiver. The transceiver may include any combination of antenna(s)234, modulators and/or demodulators 232, MIMO detector 236, receiveprocessor 238, transmit processor 220, and/or TX MIMO processor 230. Thetransceiver may be used by a processor (e.g., controller/processor 240)and memory 242 to perform aspects of any of the methods describedherein, for example, as described with reference to FIG. 5, FIGS. 6A-6B,and/or FIG. 7.

Controller/processor 240 of base station 110, controller/processor 280of UE 120, and/or any other component(s) of FIG. 2 may perform one ormore techniques associated with LBT-based resource modification andreduced COT sharing signaling for sidelink communication in unlicensedspectrum, as described in more detail elsewhere herein. For example,controller/processor 240 of base station 110, controller/processor 280of UE 120, and/or any other component(s) of FIG. 2 may perform or directoperations of, for example, process 700 of FIG. 7 and/or other processesas described herein. Memories 242 and 282 may store data and programcodes for base station 110 and UE 120, respectively. In some aspects,memory 242 and/or memory 282 may include a non-transitorycomputer-readable medium storing one or more instructions (e.g., codeand/or program code) for wireless communication. For example, the one ormore instructions, when executed (e.g., directly, or after compiling,converting, and/or interpreting) by one or more processors of the basestation 110 and/or the UE 120, may cause the one or more processors, theUE 120, and/or the base station 110 to perform or direct operations of,for example, process 700 of FIG. 7 and/or other processes as describedherein. In some aspects, executing instructions may include running theinstructions, converting the instructions, compiling the instructions,and/or interpreting the instructions, among other examples.

In some aspects, the UE 120 includes means for selecting, within aresource selection window, a set of resources in which to transmit overan unlicensed sidelink channel, means for attempting an LBT procedure toinitiate a COT in which to transmit over the unlicensed sidelinkchannel, means for adjusting, within at least a portion of the resourceselection window, the set of resources in which to transmit over theunlicensed sidelink channel to be contiguous in at least a time domainbased at least in part on the LBT procedure succeeding, and/or means fortransmitting, over the unlicensed sidelink channel, using the set ofresources that are adjusted to be contiguous in at least the timedomain. The means for the UE 120 to perform operations described hereinmay include, for example, one or more of antenna 252, demodulator 254,MIMO detector 256, receive processor 258, transmit processor 264, TXMIMO processor 266, modulator 254, controller/processor 280, or memory282.

In some aspects, the UE 120 includes means for adjusting, within theportion of the resource selection window, the set of resources in whichto transmit over the unlicensed sidelink channel to occupy a minimumnumber of subchannels that are contiguous in a frequency domain.

In some aspects, the UE 120 includes means for determining a durationbetween a trigger indicating that the LBT procedure succeeded and anearliest resource in the portion of the resource selection window,and/or means for moving the earliest resource in the portion of theresource selection window to an earlier symbol or slot based at least inpart on the duration satisfying a threshold.

In some aspects, the UE 120 includes means for transmitting, over theunlicensed sidelink channel, sidelink control information (SCI) thatindicates non-shareable resources within the COT that are reserved forone or more initial transport block transmissions.

In some aspects, the UE 120 includes means for adjusting, within theportion of the resource selection window, the set of resources in whichto transmit over the unlicensed sidelink channel to occupy differentsubchannels based at least in part on a frequency hopping pattern.

While blocks in FIG. 2 are illustrated as distinct components, thefunctions described above with respect to the blocks may be implementedin a single hardware, software, or combination component or in variouscombinations of components. For example, the functions described withrespect to the transmit processor 264, the receive processor 258, and/orthe TX MIMO processor 266 may be performed by or under the control ofcontroller/processor 280.

As indicated above, FIG. 2 is provided as an example. Other examples maydiffer from what is described with regard to FIG. 2.

FIG. 3 is a diagram illustrating an example 300 of sidelinkcommunication, in accordance with various aspects of the presentdisclosure.

As shown in FIG. 3, a first UE 305-1 may communicate with a second UE305-2 (and one or more other UEs 305) via one or more sidelink channels310. The UEs 305-1 and 305-2 may communicate using the one or moresidelink channels 310 for P2P communications, D2D communications, V2Xcommunications (e.g., which may include V2V communications, V2Icommunications, V2P communications, and/or the like), mesh networking,and/or the like. In some aspects, the UEs 305 (e.g., UE 305-1 and/or UE305-2) may correspond to one or more other UEs described elsewhereherein, such as UE 120. In some aspects, the one or more sidelinkchannels 310 may use a PC5 interface, may operate in a high frequencyband (e.g., the 5.9 GHz band), may operate on an unlicensed or sharedfrequency band (e.g., an NR unlicensed (NR-U) frequency band), and/orthe like. Additionally, or alternatively, the UEs 305 may synchronizetiming of transmission time intervals (TTIs) (e.g., frames, subframes,slots, symbols, and/or the like) using global navigation satellitesystem (GNSS) timing.

As further shown in FIG. 3, the one or more sidelink channels 310 mayinclude a physical sidelink control channel (PSCCH) 315, a physicalsidelink shared channel (PSSCH) 320, and/or a physical sidelink feedbackchannel (PSFCH) 325. The PSCCH 315 may be used to communicate controlinformation, similar to a physical downlink control channel (PDCCH)and/or a physical uplink control channel (PUCCH) used for cellularcommunications with a base station 110 via an access link or an accesschannel. The PSSCH 320 may be used to communicate data, similar to aphysical downlink shared channel (PDSCH) and/or a physical uplink sharedchannel (PUSCH) used for cellular communications with a base station 110via an access link or an access channel.

In some aspects, the PSCCH 315 may carry SCI, which may indicate variouscontrol information used for sidelink communications. For example, insome aspects, the SCI may include a stage one SCI (SCI-1) 330, which mayinclude an indication of one or more resources (e.g., time resources,frequency resources, spatial resources, and/or the like) where varioustypes of information may be carried on the PSSCH 320, information fordecoding sidelink communications on the PSSCH 320, a quality of service(QoS) priority value, a resource reservation period, a PSSCHdemodulation reference signal (DMRS) pattern, an SCI format and a betaoffset for stage two sidelink control information (SCI-2) 335transmitted on the PSSCH 320, a quantity of PSSCH DMRS ports, amodulation coding scheme (MCS), and/or the like.

In some aspects, the information carried on the PSSCH 320 may includethe SCI-2 335 and/or data 340. The SCI-2 335 may include various typesof information, such as a hybrid automatic repeat request (HARQ) processID, a new data indicator (NDI) associated with the data 340 carried onthe PSSCH 320, a source identifier, a destination identifier, a channelstate information (CSI) report trigger, and/or the like. In someaspects, a UE 305 may transmit both the SCI-1 330 and the SCI-2 335. Insome aspects, a UE 305 may transmit only SCI-1 330, in which case one ormore types of the information that would otherwise be transmitted in theSCI-2 335 may be transmitted in the SCI-1 330 instead.

In some aspects, the PSFCH 325 may be used to communicate sidelinkfeedback 345, such as HARQ feedback (e.g., acknowledgement or negativeacknowledgement (ACK/NACK) information), transmit power control (TPC), ascheduling request (SR), and/or the like.

In some aspects, the one or more sidelink channels 310 may use resourcepools. For example, a scheduling assignment (e.g., included in SCI 330)may be transmitted in sub-channels using specific resource blocks (RBs)across time. In some aspects, data transmissions (e.g., on the PSSCH320) associated with a scheduling assignment may occupy adjacent RBs inthe same subframe as the scheduling assignment (e.g., using frequencydivision multiplexing). In some aspects, a scheduling assignment andassociated data transmissions are not transmitted on adjacent RBs.

In some aspects, a UE 305 may operate using a transmission mode whereresource selection and/or scheduling is performed by the UE 305 (e.g.,rather than a base station 110). In some aspects, the UE 305 may performresource selection and/or scheduling by sensing channel availability fortransmissions. For example, the UE 305 may measure a received signalstrength indicator (RSSI) parameter (e.g., a sidelink-RSSI (S-RSSI)parameter) associated with various sidelink channels, may measure areference signal received power (RSRP) parameter (e.g., a PSSCH-RSRPparameter) associated with various sidelink channels, may measure areference signal received quality (RSRQ) parameter (e.g., a PSSCH-RSRQparameter) associated with various sidelink channels, and/or the like,and may select a channel for transmission of a sidelink communicationbased at least in part on the measurement(s).

Additionally, or alternatively, the UE 305 may perform resourceselection and/or scheduling using SCI 330 received in the PSCCH 315,which may indicate occupied resources, channel parameters, and/or thelike. Additionally, or alternatively, the UE 305 may perform resourceselection and/or scheduling by determining a channel busy rate (CBR)associated with various sidelink channels, which may be used for ratecontrol (e.g., by indicating a maximum number of resource blocks thatthe UE 305 can use for a particular set of subframes).

In the transmission mode where resource selection and/or scheduling isperformed by a UE 305, the UE 305 may generate sidelink grants, and maytransmit the grants in SCI 330. A sidelink grant may indicate, forexample, one or more parameters (e.g., transmission parameters) to beused for an upcoming sidelink transmission, such as one or more resourceblocks to be used for the upcoming sidelink transmission on the PSSCH320 (e.g., for TBs 335), one or more subframes to be used for theupcoming sidelink transmission, a modulation and coding scheme (MCS) tobe used for the upcoming sidelink transmission, and/or the like. In someaspects, a UE 305 may generate a sidelink grant that indicates one ormore parameters for semi-persistent scheduling (SPS), such as aperiodicity of a sidelink transmission. Additionally, or alternatively,the UE 305 may generate a sidelink grant for event-driven scheduling,such as for an on-demand sidelink message.

As indicated above, FIG. 3 is provided as an example. Other examples maydiffer from what is described with regard to FIG. 3.

FIGS. 4A-4B are diagrams illustrating examples 400 of COT sharing forsidelink communication in unlicensed spectrum, in accordance withvarious aspects of the present disclosure.

For example, to accommodate increasing traffic demands, there have beenvarious efforts to improve spectral efficiency in wireless networks andthereby increase network capacity (e.g., via use of higher ordermodulations, advanced MIMO antenna technologies, and/or multi-cellcoordination techniques, among other examples). Another way topotentially improve network capacity is to expand system bandwidth.However, available spectrum in lower frequency bands that havetraditionally been licensed or otherwise allocated to mobile networkoperators has become very scarce. Accordingly, various technologies havebeen developed to enable operation of a cellular radio access technology(RAT) in unlicensed or other shared spectrum. For example,Licensed-Assisted Access (LAA) uses carrier aggregation on a downlink tocombine LTE in a licensed frequency band with LTE in an unlicensedfrequency band (e.g., the 2.4 and/or 5 GHz bands already populated bywireless local area network (WLAN) or “Wi-Fi” devices). In otherexamples, Enhanced LAA (eLAA) and Further Enhanced LAA (feLAA)technologies enable both uplink and downlink LTE operation in unlicensedspectrum, MulteFire is an LTE-based technology that operates inunlicensed and shared spectrum in a standalone mode, NR-U enables NRoperation in unlicensed spectrum, and/or the like. In general, whenoperating a cellular RAT in unlicensed spectrum (e.g., using LAA, eLAA,feLAA, MulteFire, and/or NR-U), one challenge that arises is the need toensure fair coexistence with incumbent (e.g., WLAN) systems that may beoperating in the unlicensed spectrum.

For example, prior to gaining access to and/or transmitting over anunlicensed channel, a transmitting device (e.g., base station 110, UE120, UE 305, and/or the like) that has a packet to transmit may need toperform an LBT procedure to contend for access to the unlicensedchannel. The LBT procedure may generally include a clear channelassessment (CCA) procedure that is performed in order to determinewhether the unlicensed channel is available (e.g., unoccupied by othertransmitters). In particular, the CCA procedure may include detecting anenergy level on the unlicensed channel and determining whether theenergy level satisfies (e.g., is less than or equal to) a threshold,sometimes referred to as an energy detection threshold and/or the like.When the energy level satisfies (e.g., does not equal or exceed) thethreshold, the CCA procedure is deemed to be successful and thetransmitting device may gain access to the unlicensed channel for aduration that may be referred to as a channel occupancy time (COT)during which the transmitting device can perform transmissions withoutperforming additional LBT operations. When the energy level does notsatisfy the threshold, the CCA procedure is unsuccessful and contentionto access the unlicensed channel may be deemed unsuccessful.

When the CCA procedure results in a determination that the unlicensedchannel band is unavailable (e.g., because the energy level detected onthe unlicensed channel indicates that another device is already usingthe channel), the CCA procedure may be performed again at a later time.In environments in which the transmitting device may be starved ofaccess to an unlicensed channel (e.g., due to WLAN activity ortransmissions by other devices), an extended CCA (eCCA) procedure may beemployed to increase the likelihood that the transmitting device willsuccessfully obtain access to the unlicensed channel. For example, atransmitting device performing an eCCA procedure may perform a randomquantity of CCA procedures (from 1 to q), in accordance with an eCCAcounter. If and/or when the transmitting device senses that the channelhas become clear, the transmitting device may start a random wait periodbased on the eCCA counter and start to transmit if the channel remainsclear over the random wait period.

Accordingly, although a wireless network can be configured to useunlicensed spectrum to achieve faster data rates, provide a moreresponsive user experience, offload traffic from a licensed spectrum,and/or the like, the need to ensure fair coexistence with incumbentsystems (e.g., WLAN devices) may hamper efficient usage of theunlicensed spectrum. For example, even when there is no interference,the LBT procedure used to ensure that no other devices are already usingthe channel introduces a delay before transmissions can start, which maydegrade user experience, result in unacceptable performance forlatency-sensitive or delay-sensitive applications, and/or the like.Furthermore, these problems may be exacerbated when the initial CCAprocedure is unsuccessful, as the transmitting device can transmit onthe channel only after performing an additional quantity of CCAprocedures and determining that the channel has become clear andremained clear for a random wait period. Furthermore, in some cases, theCOT obtained by an initiating transmitting device may have a durationthat is longer than necessary for the transmitting device to perform thedesired transmissions, which may lead to inefficient usage of theunlicensed channel.

Accordingly, in some cases, a wireless network may enable a COT obtainedby a transmitting device to be shared with other nodes in order toimprove access, efficiency, and/or the like for an unlicensed channel.For example, in downlink-to-uplink COT sharing over an access link, abase station may acquire a COT with an eCCA, and the COT may be sharedwith one or more UEs (e.g., UE 120, UE 305, and/or the like) that canthen transmit uplink signals within the COT that was acquired by thebase station 110. In this case, a UE attempting to initiate an uplinktransmission within the COT shared with the base station can perform anuplink transmission without having to perform an LBT procedure (e.g., aCategory-1 LBT procedure, also referred to as no LBT), or the UE mayperform the uplink transmission after performing a one-shot CCA with ashorter LBT procedure (e.g., a Category-2 LBT procedure when thedownlink-to-uplink gap duration is between 16 μs and 25 μs and/or aCategory-1 LBT procedure when a downlink-to-uplink gap duration is lessthan or equal to 16 μs).

Additionally, or alternatively, a wireless network may supportuplink-to-downlink COT sharing from a UE to a base station over anaccess link. For example, a UE may perform a Category-4 LBT procedure toinitiate a COT (e.g., for a configured grant PUSCH or a scheduled uplinktransmission), which can be shared with the base station via groupcommon uplink control information (GC-UCI) that indicates a startingpoint and duration of the remaining portion of the COT to be shared withthe base station. For example, the UE may perform the Category-4 LBTprocedure to initiate a COT having a 4 millisecond (ms) duration, andmay only use 1 ms of the COT such that the remaining 3 ms of the COT canbe shared with another device. In this case, the base station may needto acquire the remaining portion of the COT immediately after the lasttransmission by the UE in the earlier (used) portion of the COT byperforming Category-1 or Category-2 LBT sensing using a 16 μs gap or a25 μs gap before the transmission by the base station. In this way, thebase station may transmit control and/or broadcast signals and/orchannels for any UE served by the base station, provided that thetransmission contains a downlink signal, channel, and/or othertransmission (e.g., a PDSCH, PDCCH, reference signal, and/or the like)intended to be received by the UE that initiated the COT.

Additionally, or alternatively, a wireless network may support UE-to-UECOT sharing over a sidelink. For example, as shown in FIG. 4A, and byreference number 410, a COT acquired by an initiating UE (e.g., UE305-1) may be shared with another UE (e.g., UE 305-2) in a frequencydivision multiplexing (FDM) mode by dividing the COT into multipleinterlaces (e.g., time periods during which one or more UEs may performtransmit operations). For example, as shown in FIG. 4A, the initiatingUE may use one or more sidelink resources (e.g., time and frequencyresources) to transmit in a first interlace after the COT has beenacquired, and a responding UE may use sidelink frequency resources thatare non-overlapping with sidelink frequency resources used by theinitiating UE to perform transmit operations in subsequent interlaces.Accordingly, as shown in FIG. 4A, FDM or interlace-based COT sharing mayintroduce short transmission gaps between interlaces to allow other UEsto perform transmit operations in subsequent interlaces during a sharedCOT, and SCI transmitted by the initiating UE may carry information tosupport the interlace-based COT sharing. For example, SCI that containsCOT sharing information may be treated as a COT sharing grant from theinitiating UE that is sharing the COT, and all responding UEs that areeligible to share the COT (e.g., based on a distance metric, a groupidentifier, and/or other information) may take the SCI as a COT sharinggrant. In this case, a responding UE may perform a Category-1 orCategory-2 LBT procedure prior to transmitting at any time up to the endof the COT, and a transmission gap limit may not apply (e.g., UEssharing the COT can start to transmit anywhere within the shared COTregion even if there is a greater than 25 μs gap between thetransmission and the end of the last transmission by the COT-initiatingUE).

Additionally, or alternatively, as shown by reference number 420,UE-to-UE COT sharing may be enabled in a time division multiplexing(TDM) mode. In this case, the total COT may be divided into an initialtime period during which the initiating UE may perform transmissions,which may include one or more SCI transmissions that include aCOT-sharing signal to indicate when the initial transmission will end, aremaining duration of the COT that is available for sharing, and/or thelike. Accordingly, one or more responding UEs may monitor the SCItransmitted by other UEs (e.g., the initiating UE) to recover COTsharing information that can be used to perform transmissions during atime period that corresponds to a shared COT.

Accordingly, as described above, UE-to-UE COT sharing may enable betteraccess to unlicensed spectrum, more efficient usage of unlicensedspectrum, and/or the like by enabling multiple UEs to performtransmissions during a COT that is obtained by an initiating UE (e.g., aUE that successfully performed a Category-4 LBT procedure to acquireaccess to an unlicensed channel). However, in some cases, implementingUE-to-UE COT sharing using the FDM and/or TDM schemes shown in FIG. 4Amay be associated with inefficient resource usage. For example, in theFDM and TDM schemes shown in FIG. 4A, the UE initiating the COTgenerally finishes transmitting at the beginning of the COT and thenshares the remaining (unused) portion of the COT with other UEs. As aresult, there may be inefficient usage of frequency resources in theearlier (used) portion of the COT. For example, the UE initiating theCOT may occupy only one or two subchannels and/or interlaces in the usedportion of the COT, meaning that other UEs could potentially conductsimultaneous transmissions in the used portion of the COT usingsubchannels and/or interlaces that are not occupied by theCOT-initiating UE (e.g., because a sidelink UE is not expected toperform unicast transmissions to multiple UEs at the same time, andtherefore does not need to utilize all available frequency resources).

Accordingly, some aspects described herein may enable UE-to-UE COTsharing during a used portion of a shared COT (e.g., while theinitiating UE is still transmitting). For example, as shown in FIG. 4B,and by reference number 430, UE-to-UE COT sharing while theCOT-initiating UE is transmitting may be enabled by dividing a COTinitiated by a UE into an FDM region in which the COT-initiating UEreserves a set of time and frequency resources reserved to transmissionsby the COT-initiating UE and a TDM region in which other UEs sharing theCOT may transmit. In this case, as shown by reference number 432, SCImay include a COT sharing signal (e.g., COT system information (COT-SI))that indicates shareable resources in a time and frequency domain. Forexample, in FIG. 4B, the shaded rectangles may indicate shareableresources that other UEs can use to transmit without colliding withnon-shareable resources reserved for transmissions by the COT-initiatingUE.

Although this approach may improve resource utilization within a sharedCOT by allowing other UEs to join and conduct transmissions over theunlicensed channel concurrently with the COT-initiating UE, the COTsharing signal may be associated with a large overhead in cases wherethe shareable resources are disjoint and varying across the COT. Forexample, the UE initiating the COT may select different subchannels thatare used for transmissions in different slots or symbols within the COTin order to gain frequency diversity. Furthermore, the UE may use alegacy sidelink resource selection algorithm to randomly selectsubchannels and/or slots within a resource selection window, whichgenerally makes the shareable resources highly disjoint. Accordingly, asshown by reference number 434, the COT sharing signal may have a largeoverhead in cases where the shareable resources are disjoint across theshared COT (e.g., because the COT sharing signal needs to indicate arectangle that corresponds to each set of shareable resources in thetime and frequency domain and needs to further indicate the TDM regionthat occurs after the COT-initiating UE has finished transmitting). Thepotentially large overhead of the COT sharing signal may be especiallyproblematic in a sidelink configuration, where the COT sharing signalmay be carried in SCI-1 to enable a reduced processing timeline andpower saving. For example, SCI-1 is carried over a PSCCH and has a smallpayload size to enable decoding by all UEs, and may therefore be unableto accommodate a COT sharing signal with a large payload. Furthermore,SCI-2 carried over a PSSCH may be unsuitable to carry the COT sharingsignal because SCI-2 is not decoded by all UEs and/or some UEs may lackcapabilities to support SCI-2.

Some aspects described herein relate to techniques and apparatuses toenable an LBT-based resource modification and reduced COT sharingsignaling for sidelink communication in unlicensed spectrum. Forexample, as described herein, a UE that has one or more packets totransmit may initially perform random resource selection within aresource selection window, as the UE may be unable to determine prior toa successful LBT procedure whether the resources that are selected willbe within a COT initiated by the UE or piggybacked on a shared COTinitiated by a different UE. In some aspects, the UE may attempt an LBTprocedure (e.g., a Category-4 LBT procedure), and may rearrange orotherwise adjust the resources that were initially selected to becontiguous in a time domain and/or clustered in a frequency domain basedon the LBT procedure succeeding. In this way, the UE may transmit SCIincluding a COT sharing signal to block other UEs from performinginterfering transmissions in the used COT region with contiguous and/orclustered transmission, and adjusting the reserved resources to becontiguous in the time domain and/or clustered in frequency domain mayenable a reduced overhead for signaling the shareable resources. Forexample, the UE initiating the COT may transmit SCI to indicatenon-shareable resources (e.g., the time and frequency resources reservedto initial transmissions by the UE), and responding UEs may select otherresources, excluding the non-shareable resources, to use fortransmissions in the used portion of the shared COT. Additionally, oralternatively, the UE may select non-shareable resources according to afrequency hopping pattern, and the SCI indicating non-shareableresources may include information to enable responding devices to derivethe frequency hopping pattern used by the COT-initiating UE (andtherefore the resources to exclude when selecting resources in the usedregion of the shared COT).

As indicated above, FIGS. 4A-4B are provided as examples. Other examplesmay differ from what is described with regard to FIGS. 4A-4B.

FIG. 5 is a diagram illustrating an example 500 associated withLBT-based resource modification for sidelink communication in unlicensedspectrum, in accordance with various aspects of the present disclosure.

For example, as shown by reference number 510, a UE may trigger asidelink resource selection in a slot n-T₁, where n-T₁ is a time whenone or more packets corresponding to one or more initial transport blocktransmissions arrive, and T₁ is duration between the time when the oneor more arrive the UE and a time when a first packet is to betransmitted. In some aspects, when the one or more packets arrive at theUE, the UE may determine whether there is a shared COT available toexploit (e.g., within a duration T₂ after the time when the one or morepackets arrive at the UE). In cases where the UE determines that anothershared COT is available, the UE may transmit the one or more packets inthe shared COT (e.g., by performing a Type-0 random resource selectionin an effective resource selection window that is defined for aremaining COT shared by another UE based at least in part on a COTsharing signal transmitted by the other UE that initiated the sharedCOT).

Alternatively, in cases where the UE determines that a shared COT isunavailable, the UE may perform random resource selected in a projectedused COT region. For example, as shown in FIG. 5, the UE may determine aprojected Category-4 LBT completion timeline 512 (e.g., a projectedduration for performing a successful Category-4 LBT procedure needed toinitiate a COT), and may further determine a resource selection windowthat covers a time period associated with the packets to be transmittedby the UE. For example, in FIG. 5, five (5) packets numbered 1-5 mayarrive at the UE, and a time period in which the 5 packets are to betransmitted may define the resource selection window. However, becausethe UE may be required to perform a successful Category-4 LBT procedurebefore transmitting, an effective resource selection window 514 mayencompass a reduced portion of the overall resource selection windowthat accounts for the projected Category-4 LBT completion timeline 512.For example, the UE may perform a Type-1 random resource selection inthe effective resource selection window 514, which generally correspondsto a projected used COT sharing region 520 (e.g., a region of a COT thatis used for transmission by the initiating UE and shared with otherUEs). In this case, a portion of the projected COT that occurs after thetransmissions that are scheduled for the UE (e.g., after the projectedused COT sharing region 520) may be a remaining COT region 522 thatother UEs can join by performing a successful Category-1 or Category-2LBT procedure.

Accordingly, as shown in FIG. 5, the UE may perform a random resourceselection within the effective resource selection window 514corresponding to the projected used COT sharing region 520. For example,among the five packets that arrive in slot n-T₁, the UE may performrandom resource selection for the three packets that are in theeffective resource selection window 514 corresponding to the projectedused COT sharing region 520. Accordingly, resources for the first twopackets (numbered 1 and 2) are excluded from the random resourceselection because the first two packets are within a projectedcontention window countdown dead zone (e.g., occur during the projectedCategory-4 LBT completion timeline). For example, resource selection isperformed at a medium access control (MAC) layer and the LBT procedureis performed at a physical (PHY) layer, which can result in uncertaintyas to when the effective resource selection window 514 is to begin. Forexample, the MAC layer may select a contention window based on apriority class associated with the traffic to be transmitted, and thePHY layer may randomly select a countdown value for performing the LBTprocedure based on the value of the contention window indicated by theMAC layer. Accordingly, the MAC layer may be unable to determine thecountdown value used by the PHY layer, the MAC layer may perform theinitial random resource selection within the effective resourceselection window 514 based on the maximum duration for the projectedCategory-4 LBT completion timeline 512.

Accordingly, in cases where the UE attempts and performs a successfulCategory-4 LBT procedure to initiate a COT, the UE may generally startto transmit on one or more subchannels in the used COT sharing region520. In such cases, the transmissions by the UE may block other nearbyUEs from performing a successful Category-4 LBT procedure on each of thesubchannels that are occupied by the UE. As described above, this mayresult in inefficient usage of frequency resources and/or may lead toCOT sharing signaling having a large overhead. For example, randomresource selection at the initial stage (e.g., prior to the UEperforming a successful Category-4 LBT procedure to initiate a COT) maybe useful to reduce a probability that the resource(s) selected by theUE will collide with non-shareable resources in a COT initiated byanother UE (e.g., because the UE initially cannot know whether therandomly selected resource(s) will be in a COT initiated by the UE orpiggybacked in an FDM mode in a used COT region shared with anotherinitiating UE. However, if another shared COT is unavailable to exploitand the UE is able to perform a successful Category-4 LBT procedure, theUE does not have to respect resources that may be reserved by other UEsand may select any suitable resources in the COT that was initiated bythe UE. In other words, the random resource selection algorithm that theUE employs to perform the initial resource selection is generallydesigned to avoid collisions in licensed spectrum, but avoiding suchcollisions is unnecessary in unlicensed spectrum because the Category-4LBT procedure ensures that there are no other devices transmitting onthe unlicensed subchannels.

Accordingly, as shown by reference number 530, the UE may trigger anadjustment to the selected resources within the effective resourceselection window 514 based at least in part on a successful Category-4LBT procedure. In some aspects, the UE may trigger the adjustment basedat least in part on determining that an attempted Category-4 LBTprocedure was successful, and that the LBT success occurred at leastn-T₃ before a preselected resource (e.g., a resource selected at slot n)is confirmed, where T₃ is a minimum duration prior to a transmissionwhen resource reselection or modification at the PHY layer is feasible.In this case, as shown in FIG. 5, the preselected resources are adjustedto be contiguous in a time domain, and may be further adjusted to occupya minimum number of subchannels. For example, one or more preselectedresources that occur later within the effective resource selectionwindow 514 may be moved to earlier time resources (e.g., earlier symbolsor slots) to close transmission gaps, and subchannels associated withpreselected resources that occur later within the effective resourceselection window 514 may be aligned with a subchannel associated with afirst resource within the effective resource selection window 514. Forexample, as shown in FIG. 5, resource 4 is aligned with a subchannelselected for resource 1, and resource 5 is moved to a preceding slot toclose a transmission gap and also aligned with the subchannel selectedfor resource 1. Additionally, or alternatively, in cases where aparticular subchannel is occupied in a given slot, another resource inthe same slot may be moved to an adjacent subchannel such that theresources occupy a minimum number of subchannels. Furthermore, in someaspects, the selected resources may be adjusted such that a 16 μs gap isprovided between consecutive transmissions in order to allow other UEsto perform a Category-2 LBT procedure to transmit in the used COTsharing region 520. Accordingly, because resources 4 and 5 are adjustedin the time and/or frequency domain, the adjustment may be triggered ifthe Category-4 LBT procedure succeeds at least T₃ prior to the timeresources associated with resources 4 and 5.

In some aspects, the adjustment to the resource selection may beassociated with one or more initial transport block transmissions, andany resources previously reserved for retransmissions by the UEinitiating the COT may be maintained. For example, the resourcespreviously reserved for retransmissions by the initiating UE may beindicated in SCI-1 that other UEs may be in the process of decoding.Accordingly, other UEs that join the COT may respect the resourcereservation(s) for the retransmissions even if the reserved resourcesare in a shareable resource region, as described in more detail below.In this case, where one or more resources reserved for a retransmissionare in the same subchannel occupied by a first prescheduled resourcewithin the used COT sharing region 520, the first prescheduled resourcemay be adjusted to occupy the same slot as the resource(s) reserved fora retransmission in a next available subchannel adjacent to thesubchannel reserved for the retransmission. In this way, the adjustmentto the resource selection ensures contiguous transmission within theused COT sharing region 520, as the retransmission on reserved resourcesmay or may not occur (e.g., depending on HARQ feedback for the initialtransmission).

In some aspects, as described above, the Category-4 LBT procedure may beperformed at the PHY layer, which may trigger the MAC layer to performthe resource modification to adjust the preselected resources to becontiguous in the time domain and/or the frequency domain when theCategory-4 LBT procedure is successful. For example, at the time thatthe resources are preselected, the preselected resources are unconfirmed(e.g., because the Category-4 LBT procedure may fail) and are notindicated as reserved resources in SCI that is transmitted over-the-airto other UEs. Accordingly, the resource reselection or modification maybe triggered at the MAC layer based at least in part on the successfulCategory-4 LBT procedure occurring at least T₃ ahead of a resource thatis adjusted in the time domain and/or the frequency domain, where T₃ isa minimum duration to process the resource adjustment. Furthermore, insome aspects, the MAC layer may adjust the first resource (e.g., areference resource that defines the subchannel to which later resourcesare moved) in cases where a duration between a trigger indicating thatthe Category-4 LBT succeeded and a start of the first resource satisfies(e.g., equals or exceeds) a threshold. For example, as described above,the projected Category-4 LBT completion timeline 512 may be based on aworst-case scenario (e.g., the PHY layer selecting a maximum countdownvalue), whereby the Category-4 LBT procedure may be successful earlierthan the projected Category-4 LBT completion timeline 512 that isdetermined by the MAC layer. For example, when the MAC layer signals acontention window value to the PHY layer, the PHY layer selects a randomnumber, q, between zero and the contention window value, and the MAClayer determines the projected Category-4 LBT completion timeline 512based on the maximum value for q (e.g., the contention window value).When q counts down to zero, the PHY layer attempts the Category-4 LBTprocedure and may trigger the MAC layer to perform resource modificationif the Category-4 LBT procedure is successful. Accordingly, if aduration between the trigger received at the MAC layer to indicate aCategory-4 LBT success and the first (reference) resource in theeffective resource selection window 514 satisfies a threshold (e.g.,equals or exceeds T₃), the MAC layer may move the first resource to anearlier slot and later resources within the effective resource selectionwindow 514 may be adjusted accordingly (e.g., moved to earlier slots tobe contiguous with the first resource in at least the time domain).

As indicated above, FIG. 5 is provided as an example. Other examples maydiffer from what is described with regard to FIG. 5.

FIGS. 6A-6B are diagrams illustrating examples 600 associated withreduced COT sharing signaling for sidelink communication in unlicensedspectrum, in accordance with various aspects of the present disclosure.

For example, as shown in FIGS. 6A-6B, a UE that performs a successfulCategory-4 LBT procedure may initiate a COT that includes an initialportion, which may be referred to herein as a used COT sharing region,in which the UE conducts one or more transmissions. As further shown inFIGS. 6A-6B, the COT initiated by the UE may include a later portion(after the last transmission by the initiating UE) that is shared withother UEs, which may be referred to herein as a remaining COT region. Asdescribed in further detail above with reference to FIG. 5, a UE thatinitiates a COT may adjust a set of resources that are reserved toinitial transport block transmissions to be contiguous in a time domainand/or a frequency domain based at least in part on a successfulCategory-4 LBT procedure. In this way, the adjustment to the (initiallyrandom) resource selection may result in the resources reserved to theinitial transport block transmissions being less disjoint. Accordingly,as described herein, adjusting the resources within the used COT sharingregion to be contiguous in the time and/or frequency domain may enablecompact signaling to indicate the occupied resources that are reservedfor the initiating UE. In this way, the UE may transmit a COT sharingsignaling in SCI-1 to reduce a processing timeline and reduce complexityand/or power consumption (e.g., because SCI-1 has a small payload sizeand is decoded by all UEs).

For example, as shown by reference number 610, the UE that initiates theCOT (e.g., UE₀) may transmit SCI that includes a COT sharing signal toindicate non-shareable (e.g., occupied) resources in the used COTsharing region. In general, as described above, the non-shareableresources indicated in the COT sharing signal may be associated with oneor more initial transport block transmissions. For example,retransmission resources may be reserved by SCI-1 that the UE transmitsover-the-air prior to initiating the COT, and other UEs may already bedecoding the SCI-1 that indicates the reserved retransmission resourcesbefore the COT is initiated. Accordingly, at the time that the resourcesare selected for the retransmission, the UE may avoid placing theretransmission resources in a fixed subchannel because the UE cannotdetermine at that time whether the retransmissions will be transmittedin a COT shared by another UE or a COT initiated by the UE. Furthermore,in cases where the retransmissions are in an FDM (used COT sharing)region associated with another UE, the retransmission could potentiallycollide with non-shareable resources reserved by the COT-sharing UE.Accordingly, random resource selection may be performed forretransmissions to reduce a probability of collisions with non-shareableresources reserved by a COT-sharing UE. However, for initial transportblock transmissions, the preselected resources may be adjusted to becontiguous in the time domain and/or the frequency domain in order toreduce the number of non-shareable resources, which may enable reducedCOT sharing signaling.

For example, as described above, the UE that initiates the COT adjuststhe resources to be contiguous within the used COT sharing region in atleast the time domain based on a successful Category-4 LBT procedure,and may further adjust the resources to be contiguous in the frequencydomain (e.g., occupying the same subchannel or adjacent subchannels).For example, as shown in FIG. 6A, the UE initiating the COT has adjusteda set of resources to be contiguous in time (e.g., back-to-back), andall resources are aligned with the subchannel selected for the firstresource (subchannel #0) except for a fifth resource that iscontemporaneous with a sixth resource. Accordingly, in this case, thefifth resource is assigned to a subchannel that is adjacent to thesubchannel selected for the first resource (subchannel #1). In thiscase, the resource allocation in the used COT sharing region iscontiguous in the time domain and the frequency domain, whereby the COTsharing signal in the SCI may signal a starting subchannel and an endingsubchannel that the new transport blocks are occupying in the used COTsharing region. In other words, the COT sharing signal indicates aminimum rectangle (e.g., a starting and ending subchannel, and astarting and ending symbol or slot) that the new transport blocks areoccupying in the used COT sharing region. Accordingly, the COT sharingsignal may indicate that the UE initiating the COT is committed to notoccupy resources for initial transmissions outside the minimum rectanglethat defines the resources occupied by the new transport blocks(although resources previously reserved for retransmissions may beoutside the starting and ending subchannels and/or the starting andending transmission time intervals). Additionally, or alternatively, oneor more SCI transmissions at the beginning of the COT may indicate themaximum subchannels, interlaces, and/or resource block (RB) sets thatare occupied by the new transport blocks within the used COT sharingregion.

Accordingly, in some aspects, the SCI may generally indicate thenon-shareable resources that are reserved for new transport blocktransmissions by the COT-initiating UE, whereby shareable resources mayinclude all resources in the RB sets that cleared the Category-4 LBTprocedure excluding the non-shareable resources indicated in the SCI. Inthis way, as shown by reference number 620, other UEs joining the COTmay select resource candidates within the shareable resources accordingto a default sidelink resource selection algorithm (e.g., randomresource selection). Furthermore, to the extent that any resourcesreserved to retransmissions by the COT-initiating UE fall within theshareable resources, the sidelink resource selection or reselectionalgorithm may be designed to resolve any such collisions (e.g., byavoiding previously reserved resources and/or overriding the previousresource reservation with a high priority transmission). Furthermore, incases where multiple UEs are joining in the used COT sharing region, asidelink congestion control algorithm may be used to limit collisions onthe shareable resources within the used COT sharing region. As furthershown by reference number 625, in the remaining COT region, other UEsmay join with a Category-1 or Category-2 LBT procedure, as describedabove. For example, different UEs can share the COT using a TDMconfiguration across different slots and/or an FDM configuration ondifferent subchannels and/or interlaces. In an FDM mode, gaps may beprovided at slot boundaries for a transmission burst to provide laterjoining UEs an opportunity to clear LBT and join in transmitting duringthe remaining COT region.

In general, in the example described above with reference to FIG. 6A, aCOT-initiating UE that performs a successful Category-4 LBT procedureadjusts an initially selected (or preselected) set of resources to becontiguous in the time domain and further adjusts the set of resourcesto occupy the same subchannel or adjacent subchannels. Accordingly,adjusting the set of resources to be contiguous may enable COT sharingsignaling with a reduced overhead because the COT-initiating UE canindicate shareable resources by signaling non-shareable resourcesaccording to a starting and ending subchannel. However, adjusting theset of resources to be contiguous in the frequency domain (e.g.,occupying adjacent subchannels) sacrifices gains that may be achievedthrough frequency diversity, which may be problematic for anon-interlaced waveform. Accordingly, as shown in FIG. 6B, theCOT-initiating UE may follow a frequency hopping pattern over differentsubchannels when transmitting in the used COT sharing region. In thiscase, the frequency hopping pattern may be a function of one or moreidentifiers, such as an identifier associated with the UE and/or a slotindex, among other examples. In some aspects, the function may be knownto all of the sidelink UEs (e.g., based on a wireless communicationstandard and/or sidelink signaling exchanged between the UEs, amongother examples).

Accordingly, as shown by reference number 640, the SCI transmitted bythe COT-initiating UE may include a COT sharing signal that indicatesinformation to enable other UEs to derive the frequency hopping patternused by the COT-initiating UE. For example, as shown, the COT may covermultiple subchannels in different slots, and the frequency hoppingpattern may define a frequency location for a first allocatedsubchannel, with subsequent frequency locations depending on thefrequency location for the first allocated subchannel. Accordingly, theCOT sharing signal transmitted by the COT-initiating UE may include theidentifier that the COT-initiating UE used to derive the frequencyhopping pattern. In this way, as shown by reference number 650, otherUEs joining the COT may derive the frequency hopping pattern of theinitiating UE based at least in part on the COT sharing signal, and mayselect resource candidates that exclude the frequency locations occupiedby the COT-initiating UE. Furthermore, as shown by reference number 655,in the remaining COT region, other UEs may join with a Category-1 orCategory-2 LBT procedure in a similar manner as described above. In thisway, the COT-initiating UE may utilize frequency hopping to achieve afrequency diversity gain, and the COT sharing signal may have a lowoverhead because the only information to be signaled is the identifierused to derive the frequency hopping pattern.

As indicated above, FIGS. 6A-6B are provided as examples. Other examplesmay differ from what is described with regard to FIGS. 6A-6B.

FIG. 7 is a diagram illustrating an example process 700 performed, forexample, by a UE, in accordance with various aspects of the presentdisclosure. Example process 700 is an example where the UE (e.g., UE 120and/or UE 305, among other examples) performs operations associated withLBT-based resource modification and reduced COT sharing signaling forsidelink communication in unlicensed spectrum.

As shown in FIG. 7, in some aspects, process 700 may include selecting,within a resource selection window, a set of resources in which totransmit over an unlicensed sidelink channel (block 710). For example,the UE (e.g., using resource configuration component 808, depicted inFIG. 8) may select, within a resource selection window, a set ofresources in which to transmit over an unlicensed sidelink channel, asdescribed above.

As further shown in FIG. 7, in some aspects, process 700 may includeattempting an LBT procedure to initiate a COT in which to transmit overthe unlicensed sidelink channel (block 720). For example, the UE (e.g.,using LBT component 810, depicted in FIG. 8) may attempt an LBTprocedure to initiate a COT in which to transmit over the unlicensedsidelink channel, as described above.

As further shown in FIG. 7, in some aspects, process 700 may includeadjusting, within at least a portion of the resource selection window,the set of resources in which to transmit over the unlicensed sidelinkchannel to be contiguous in at least a time domain based at least inpart on the LBT procedure succeeding (block 730). For example, the UE(e.g., using resource configuration component 808, depicted in FIG. 8)may adjust, within at least a portion of the resource selection window,the set of resources in which to transmit over the unlicensed sidelinkchannel to be contiguous in at least a time domain based at least inpart on the LBT procedure succeeding, as described above.

As further shown in FIG. 7, in some aspects, process 700 may includetransmitting, over the unlicensed sidelink channel, using the set ofresources that are adjusted to be contiguous in at least the time domain(block 740). For example, the UE (e.g., using transmission component804, depicted in FIG. 8) may transmit, over the unlicensed sidelinkchannel, using the set of resources that are adjusted to be contiguousin at least the time domain, as described above.

Process 700 may include additional aspects, such as any single aspect orany combination of aspects described below and/or in connection with oneor more other processes described elsewhere herein.

In a first aspect, process 700 includes adjusting, within the portion ofthe resource selection window, the set of resources in which to transmitover the unlicensed sidelink channel to occupy a minimum number ofsubchannels that are contiguous in a frequency domain.

In a second aspect, alone or in combination with the first aspect, oneor more resources that are later in the time domain are adjusted to becontiguous in one or more of the time domain or a frequency domain withan earliest resource within the portion of the resource selectionwindow.

In a third aspect, alone or in combination with one or more of the firstand second aspects, the set of resources that are adjusted within theportion of the resource selection window are preselected for one or moreinitial transport block transmissions.

In a fourth aspect, alone or in combination with one or more of thefirst through third aspects, the set of resources are adjusted at a MAClayer based at least in part on a trigger at a PHY layer indicating thatthe LBT procedure succeeded.

In a fifth aspect, alone or in combination with one or more of the firstthrough fourth aspects, adjusting the set of resources includesdetermining a duration between the trigger indicating that the LBTprocedure succeeded and an earliest resource in the portion of theresource selection window, and moving the earliest resource in theportion of the resource selection window to an earlier symbol or slotbased at least in part on the duration satisfying a threshold.

In a sixth aspect, alone or in combination with one or more of the firstthrough fifth aspects, process 700 includes transmitting, over theunlicensed sidelink channel, SCI that indicates non-shareable resourceswithin the COT that are reserved for one or more initial transport blocktransmissions.

In a seventh aspect, alone or in combination with one or more of thefirst through sixth aspects, the SCI indicates the non-shareableresources based at least in part on a starting subchannel and an endingsubchannel reserved for the one or more initial transport blocktransmissions.

In an eighth aspect, alone or in combination with one or more of thefirst through seventh aspects, the SCI further indicates a maximum setof occupied subchannels, interlaces, or RB sets in the COT.

In a ninth aspect, alone or in combination with one or more of the firstthrough eighth aspects, shareable resources within the COT include allresources in the maximum set of occupied subchannels, interlaces, or RBsets, excluding the non-shareable resources.

In a tenth aspect, alone or in combination with one or more of the firstthrough ninth aspects, process 700 includes adjusting, within theportion of the resource selection window, the set of resources in whichto transmit over the unlicensed sidelink channel to occupy differentsubchannels based at least in part on a frequency hopping pattern.

In an eleventh aspect, alone or in combination with one or more of thefirst through tenth aspects, the frequency hopping pattern is based atleast in part on one or more identifiers associated with the UE, and theSCI includes the one or more identifiers associated with the UE toindicate the non-shareable resources that are reserved for the one ormore initial transport block transmissions.

Although FIG. 7 shows example blocks of process 700, in some aspects,process 700 may include additional blocks, fewer blocks, differentblocks, or differently arranged blocks than those depicted in FIG. 7.Additionally, or alternatively, two or more of the blocks of process 700may be performed in parallel.

FIG. 8 is a block diagram of an example apparatus 800 for wirelesscommunication. The apparatus 800 may be a UE, or a UE may include theapparatus 800. In some aspects, the apparatus 800 includes a receptioncomponent 802 and a transmission component 804, which may be incommunication with one another (for example, via one or more busesand/or one or more other components). As shown, the apparatus 800 maycommunicate with another apparatus 806 (such as a UE, a base station, oranother wireless communication device) using the reception component 802and the transmission component 804. As further shown, the apparatus 800may include one or more of a resource configuration component 808 or anLBT component 810, among other examples.

In some aspects, the apparatus 800 may be configured to perform one ormore operations described herein in connection with FIG. 5 and/or FIGS.6A-6B. Additionally, or alternatively, the apparatus 800 may beconfigured to perform one or more processes described herein, such asprocess 700 of FIG. 7. In some aspects, the apparatus 800 and/or one ormore components shown in FIG. 8 may include one or more components ofthe UE described above in connection with FIG. 2. Additionally, oralternatively, one or more components shown in FIG. 8 may be implementedwithin one or more components described above in connection with FIG. 2.Additionally, or alternatively, one or more components of the set ofcomponents may be implemented at least in part as software stored in amemory. For example, a component (or a portion of a component) may beimplemented as instructions or code stored in a non-transitorycomputer-readable medium and executable by a controller or a processorto perform the functions or operations of the component.

The reception component 802 may receive communications, such asreference signals, control information, data communications, or acombination thereof, from the apparatus 806. The reception component 802may provide received communications to one or more other components ofthe apparatus 800. In some aspects, the reception component 802 mayperform signal processing on the received communications (such asfiltering, amplification, demodulation, analog-to-digital conversion,demultiplexing, deinterleaving, de-mapping, equalization, interferencecancellation, or decoding, among other examples), and may provide theprocessed signals to the one or more other components of the apparatus806. In some aspects, the reception component 802 may include one ormore antennas, a demodulator, a MIMO detector, a receive processor, acontroller/processor, a memory, or a combination thereof, of the UEdescribed above in connection with FIG. 2.

The transmission component 804 may transmit communications, such asreference signals, control information, data communications, or acombination thereof, to the apparatus 806. In some aspects, one or moreother components of the apparatus 806 may generate communications andmay provide the generated communications to the transmission component804 for transmission to the apparatus 806. In some aspects, thetransmission component 804 may perform signal processing on thegenerated communications (such as filtering, amplification, modulation,digital-to-analog conversion, multiplexing, interleaving, mapping, orencoding, among other examples), and may transmit the processed signalsto the apparatus 806. In some aspects, the transmission component 804may include one or more antennas, a modulator, a transmit MIMOprocessor, a transmit processor, a controller/processor, a memory, or acombination thereof, of the UE described above in connection with FIG.2. In some aspects, the transmission component 804 may be co-locatedwith the reception component 802 in a transceiver.

The resource configuration component 808 may select, within a resourceselection window, a set of resources in which to transmit over anunlicensed sidelink channel. The LBT component 810 may attempt an LBTprocedure to initiate a COT in which to transmit over the unlicensedsidelink channel. The resource configuration component 808 may adjust,within at least a portion of the resource selection window, the set ofresources in which to transmit over the unlicensed sidelink channel tobe contiguous in at least a time domain based at least in part on theLBT procedure succeeding. The transmission component 804 may transmit,over the unlicensed sidelink channel, using the set of resources thatare adjusted to be contiguous in at least the time domain.

The resource configuration component 808 may adjust, within the portionof the resource selection window, the set of resources in which totransmit over the unlicensed sidelink channel to occupy a minimum numberof subchannels that are contiguous in a frequency domain.

The resource configuration component 808 may determine a durationbetween the trigger indicating that the LBT procedure succeeded and anearliest resource in the portion of the resource selection window. Theresource configuration component 808 may move the earliest resource inthe portion of the resource selection window to an earlier symbol orslot based at least in part on the duration satisfying a threshold.

The transmission component 804 may transmit, over the unlicensedsidelink channel, SCI that indicates non-shareable resources within theCOT that are reserved for one or more initial transport blocktransmissions.

The resource configuration component 808 may adjust, within the portionof the resource selection window, the set of resources in which totransmit over the unlicensed sidelink channel to occupy differentsubchannels based at least in part on a frequency hopping pattern.

The number and arrangement of components shown in FIG. 8 are provided asan example. In practice, there may be additional components, fewercomponents, different components, or differently arranged componentsthan those shown in FIG. 8. Furthermore, two or more components shown inFIG. 8 may be implemented within a single component, or a singlecomponent shown in FIG. 8 may be implemented as multiple, distributedcomponents. Additionally, or alternatively, a set of (one or more)components shown in FIG. 8 may perform one or more functions describedas being performed by another set of components shown in FIG. 8.

The following provides an overview of aspects of the present disclosure:

Aspect 1: A method for wireless communication performed by a UE,comprising: selecting, within a resource selection window, a set ofresources in which to transmit over an unlicensed sidelink channel;attempting an LBT procedure to initiate a COT in which to transmit overthe unlicensed sidelink channel; and adjusting, within at least aportion of the resource selection window, the set of resources in whichto transmit over the unlicensed sidelink channel to be contiguous in atleast a time domain based at least in part on the LBT proceduresucceeding.

Aspect 2: The method of aspect 1, further comprising: adjusting, withinthe portion of the resource selection window, the set of resources inwhich to transmit over the unlicensed sidelink channel to occupy aminimum number of subchannels that are contiguous in a frequency domain.

Aspect 3: The method of any of aspects 1 through 2, wherein one or moreresources that are later in the time domain are adjusted to becontiguous in one or more of the time domain or a frequency domain withan earliest resource within the portion of the resource selectionwindow.

Aspect 4: The method of any of aspects 1 through 3, wherein the set ofresources that are adjusted within the portion of the resource selectionwindow are preselected for one or more initial transport blocktransmissions.

Aspect 5: The method of any of aspects 1 through 4, wherein the set ofresources are adjusted at a MAC layer based at least in part on atrigger at a PHY layer indicating that the LBT procedure succeeded.

Aspect 6: The method of any of aspects 1 through 5, wherein adjustingthe set of resources includes: determining a duration between a triggerindicating that the LBT procedure succeeded and an earliest resource inthe portion of the resource selection window; and moving the earliestresource in the portion of the resource selection window to an earliersymbol or slot based at least in part on the duration satisfying athreshold.

Aspect 7: The method of any of aspects 1 through 6, further comprising:transmitting, over the unlicensed sidelink channel, SCI that indicatesnon-shareable resources within the COT that are reserved for one or moreinitial transport block transmissions.

Aspect 8: The method of aspect 7, wherein the SCI indicates thenon-shareable resources based at least in part on a starting subchanneland an ending subchannel reserved for the one or more initial transportblock transmissions.

Aspect 9: The method of any of aspects 7 through 8, wherein the SCIfurther indicates a maximum set of occupied subchannels, interlaces, orRB sets in the COT.

Aspect 10: The method of aspect 9, wherein shareable resources withinthe COT include all resources in the maximum set of occupiedsubchannels, interlaces, or RB sets, excluding the non-shareableresources.

Aspect 11: The method of any of aspects 1 or 3 through 10, furthercomprising: adjusting, within the portion of the resource selectionwindow, the set of resources in which to transmit over the unlicensedsidelink channel to occupy different subchannels based at least in parton a frequency hopping pattern.

Aspect 12: The method of aspect 11, wherein the frequency hoppingpattern is based at least in part on one or more identifiers associatedwith the UE, and wherein the SCI includes the one or more identifiersassociated with the UE to indicate the non-shareable resources that arereserved for the one or more initial transport block transmissions.

Aspect 13: An apparatus for wireless communication at a first device,comprising a processor; memory coupled with the processor; andinstructions stored in the memory and executable by the processor tocause the apparatus to perform a method of any of aspects 1 through 12.

Aspect 14: A UE for wireless communication, comprising a memory and oneor more processors coupled to the memory, the memory and the one or moreprocessors configured to perform a method of any of aspects 1 through12.

Aspect 15: An apparatus for wireless communication, comprising at leastone means for performing a method of any of aspects 1 through 12.

Aspect 16: A non-transitory computer-readable medium storing code forwireless communication, the code comprising instructions executable by aprocessor to perform a method of any of aspects 1 through 12.

Aspect 17: A non-transitory computer-readable medium storing one or moreinstructions for wireless communication, the one or more instructionscomprising one or more instructions that, when executed by one or moreprocessors of a UE, cause the one or more processors to perform a methodof any of aspects 1 through 12.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the aspects to the preciseforms disclosed. Modifications and variations may be made in light ofthe above disclosure or may be acquired from practice of the aspects.

As used herein, the term “component” is intended to be broadly construedas hardware and/or a combination of hardware and software. “Software”shall be construed broadly to mean instructions, instruction sets, code,code segments, program code, programs, subprograms, software modules,applications, software applications, software packages, routines,subroutines, objects, executables, threads of execution, procedures,and/or functions, among other examples, whether referred to as software,firmware, middleware, microcode, hardware description language, orotherwise. As used herein, a processor is implemented in hardware and/ora combination of hardware and software. It will be apparent that systemsand/or methods described herein may be implemented in different forms ofhardware and/or a combination of hardware and software. The actualspecialized control hardware or software code used to implement thesesystems and/or methods is not limiting of the aspects. Thus, theoperation and behavior of the systems and/or methods were describedherein without reference to specific software code—it being understoodthat software and hardware can be designed to implement the systemsand/or methods based, at least in part, on the description herein.

As used herein, satisfying a threshold may, depending on the context,refer to a value being greater than the threshold, greater than or equalto the threshold, less than the threshold, less than or equal to thethreshold, equal to the threshold, not equal to the threshold, or thelike.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of various aspects. In fact, many ofthese features may be combined in ways not specifically recited in theclaims and/or disclosed in the specification. Although each dependentclaim listed below may directly depend on only one claim, the disclosureof various aspects includes each dependent claim in combination withevery other claim in the claim set. As used herein, a phrase referringto “at least one of” a list of items refers to any combination of thoseitems, including single members. As an example, “at least one of: a, b,or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well asany combination with multiples of the same element (e.g., a-a, a-a-a,a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or anyother ordering of a, b, and c).

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems and may be used interchangeably with “one or more.” Further, asused herein, the article “the” is intended to include one or more itemsreferenced in connection with the article “the” and may be usedinterchangeably with “the one or more.” Furthermore, as used herein, theterms “set” and “group” are intended to include one or more items (e.g.,related items, unrelated items, or a combination of related andunrelated items), and may be used interchangeably with “one or more.”Where only one item is intended, the phrase “only one” or similarlanguage is used. Also, as used herein, the terms “has,” “have,”“having,” or the like are intended to be open-ended terms. Further, thephrase “based on” is intended to mean “based, at least in part, on”unless explicitly stated otherwise. Also, as used herein, the term “or”is intended to be inclusive when used in a series and may be usedinterchangeably with “and/or,” unless explicitly stated otherwise (e.g.,if used in combination with “either” or “only one of”).

What is claimed is:
 1. A method of wireless communication performed by auser equipment (UE), comprising: selecting, within a resource selectionwindow, a set of resources in which to transmit over an unlicensedsidelink channel; attempting a listen before talk (LBT) procedure toinitiate a channel occupancy time (COT) in which to transmit over theunlicensed sidelink channel; adjusting, within at least a portion of theresource selection window, the set of resources in which to transmitover the unlicensed sidelink channel to be contiguous in at least a timedomain based at least in part on the LBT procedure succeeding; andtransmitting, over the unlicensed sidelink channel, using the set ofresources that are adjusted to be contiguous in at least the timedomain.
 2. The method of claim 1, further comprising: adjusting, withinthe portion of the resource selection window, the set of resources inwhich to transmit over the unlicensed sidelink channel to occupy aminimum number of subchannels that are contiguous in a frequency domain.3. The method of claim 1, wherein one or more resources that are laterin the time domain are adjusted to be contiguous in one or more of thetime domain or a frequency domain with an earliest resource within theportion of the resource selection window.
 4. The method of claim 1,wherein the set of resources that are adjusted within the portion of theresource selection window are preselected for one or more initialtransport block transmissions.
 5. The method of claim 1, wherein the setof resources are adjusted at a medium access control layer based atleast in part on a trigger at a physical layer indicating that the LBTprocedure succeeded.
 6. The method of claim 5, wherein adjusting the setof resources includes: determining a duration between the triggerindicating that the LBT procedure succeeded and an earliest resource inthe portion of the resource selection window; and moving the earliestresource in the portion of the resource selection window to an earliersymbol or slot based at least in part on the duration satisfying athreshold.
 7. The method of claim 1, further comprising: transmitting,over the unlicensed sidelink channel, sidelink control information (SCI)that indicates non-shareable resources within the COT that are reservedfor one or more initial transport block transmissions.
 8. The method ofclaim 7, wherein the SCI indicates the non-shareable resources based atleast in part on a starting subchannel and an ending subchannel reservedfor the one or more initial transport block transmissions.
 9. The methodof claim 7, wherein the SCI further indicates a maximum set of occupiedsubchannels, interlaces, or resource block sets in the COT.
 10. Themethod of claim 9, wherein shareable resources within the COT includeall resources in the maximum set of occupied subchannels, interlaces, orresource block sets, excluding the non-shareable resources.
 11. Themethod of claim 7, further comprising: adjusting, within the portion ofthe resource selection window, the set of resources in which to transmitover the unlicensed sidelink channel to occupy different subchannelsbased at least in part on a frequency hopping pattern.
 12. The method ofclaim 11, wherein the frequency hopping pattern is based at least inpart on one or more identifiers associated with the UE, and wherein theSCI includes the one or more identifiers associated with the UE toindicate the non-shareable resources that are reserved for the one ormore initial transport block transmissions.
 13. A user equipment (UE)for wireless communication, comprising: a memory; and one or moreprocessors operatively coupled to the memory, the memory and the one ormore processors configured to: select, within a resource selectionwindow, a set of resources in which to transmit over an unlicensedsidelink channel; attempt a listen before talk (LBT) procedure toinitiate a channel occupancy time (COT) in which to transmit over theunlicensed sidelink channel; adjust, within at least a portion of theresource selection window, the set of resources in which to transmitover the unlicensed sidelink channel to be contiguous in at least a timedomain based at least in part on the LBT procedure succeeding; andtransmit, over the unlicensed sidelink channel, using the set ofresources that are adjusted to be contiguous in at least the timedomain.
 14. The UE of claim 13, wherein the one or more processors arefurther configured to: adjust, within the portion of the resourceselection window, the set of resources in which to transmit over theunlicensed sidelink channel to occupy a minimum number of subchannelsthat are contiguous in a frequency domain.
 15. The UE of claim 13,wherein one or more resources that are later in the time domain areadjusted to be contiguous in one or more of the time domain or afrequency domain with an earliest resource within the portion of theresource selection window.
 16. The UE of claim 13, wherein the one ormore processors, when adjusting the set of resources, are configured to:determine a duration between a trigger indicating that the LBT proceduresucceeded and an earliest resource in the portion of the resourceselection window; and move the earliest resource in the portion of theresource selection window to an earlier symbol or slot based at least inpart on the duration satisfying a threshold.
 17. The UE of claim 13,wherein the one or more processors are further configured to: transmit,over the unlicensed sidelink channel, sidelink control information (SCI)that indicates non-shareable resources within the COT that are reservedfor one or more initial transport block transmissions.
 18. The UE ofclaim 17, wherein the one or more processors are further configured to:adjust, within the portion of the resource selection window, the set ofresources in which to transmit over the unlicensed sidelink channel tooccupy different subchannels based at least in part on a frequencyhopping pattern.
 19. A non-transitory computer-readable medium storing aset of instructions for wireless communication, the set of instructionscomprising: one or more instructions that, when executed by one or moreprocessors of a user equipment (UE), cause the UE to: select, within aresource selection window, a set of resources in which to transmit overan unlicensed sidelink channel; attempt a listen before talk (LBT)procedure to initiate a channel occupancy time (COT) in which totransmit over the unlicensed sidelink channel; adjust, within at least aportion of the resource selection window, the set of resources in whichto transmit over the unlicensed sidelink channel to be contiguous in atleast a time domain based at least in part on the LBT proceduresucceeding; and transmit, over the unlicensed sidelink channel, usingthe set of resources that are adjusted to be contiguous in at least thetime domain.
 20. The non-transitory computer-readable medium of claim19, wherein the one or more instructions further cause the UE to:adjust, within the portion of the resource selection window, the set ofresources in which to transmit over the unlicensed sidelink channel tooccupy a minimum number of subchannels that are contiguous in afrequency domain.
 21. The non-transitory computer-readable medium ofclaim 19, wherein one or more resources that are later in the timedomain are adjusted to be contiguous in one or more of the time domainor a frequency domain with an earliest resource within the portion ofthe resource selection window.
 22. The non-transitory computer-readablemedium of claim 19, wherein the one or more instructions, that cause theUE to adjust the set of resources, cause the UE to: determine a durationbetween a trigger indicating that the LBT procedure succeeded and anearliest resource in the portion of the resource selection window; andmove the earliest resource in the portion of the resource selectionwindow to an earlier symbol or slot based at least in part on theduration satisfying a threshold.
 23. The non-transitorycomputer-readable medium of claim 19, wherein the one or moreinstructions further cause the UE to: transmit, over the unlicensedsidelink channel, sidelink control information (SCI) that indicatesnon-shareable resources within the COT that are reserved for one or moreinitial transport block transmissions.
 24. The non-transitorycomputer-readable medium of claim 23, wherein the one or moreinstructions further cause the UE to: adjust, within the portion of theresource selection window, the set of resources in which to transmitover the unlicensed sidelink channel to occupy different subchannelsbased at least in part on a frequency hopping pattern.
 25. An apparatusfor wireless communication, comprising: means for selecting, within aresource selection window, a set of resources in which to transmit overan unlicensed sidelink channel; means for attempting a listen beforetalk (LBT) procedure to initiate a channel occupancy time (COT) in whichto transmit over the unlicensed sidelink channel; means for adjusting,within at least a portion of the resource selection window, the set ofresources in which to transmit over the unlicensed sidelink channel tobe contiguous in at least a time domain based at least in part on theLBT procedure succeeding; and means for transmitting, over theunlicensed sidelink channel, using the set of resources that areadjusted to be contiguous in at least the time domain.
 26. The apparatusof claim 25, further comprising: means for adjusting, within the portionof the resource selection window, the set of resources in which totransmit over the unlicensed sidelink channel to occupy a minimum numberof subchannels that are contiguous in a frequency domain.
 27. Theapparatus of claim 25, wherein one or more resources that are later inthe time domain are adjusted to be contiguous in one or more of the timedomain or a frequency domain with an earliest resource within theportion of the resource selection window.
 28. The apparatus of claim 25,wherein the means for adjusting the set of resources includes: means fordetermining a duration between a trigger indicating that the LBTprocedure succeeded and an earliest resource in the portion of theresource selection window; and means for moving the earliest resource inthe portion of the resource selection window to an earlier symbol orslot based at least in part on the duration satisfying a threshold. 29.The apparatus of claim 25, further comprising: means for transmitting,over the unlicensed sidelink channel, sidelink control information (SCI)that indicates non-shareable resources within the COT that are reservedfor one or more initial transport block transmissions.
 30. The apparatusof claim 29, further comprising: means for adjusting, within the portionof the resource selection window, the set of resources in which totransmit over the unlicensed sidelink channel to occupy differentsubchannels based at least in part on a frequency hopping pattern.